Method and means for abrading lenses



- Jan. 11, 1938. 5, ANDERSQN 2,105,175

METHOD AND MEANS FOR ABBADING LENSES Original File d March 7, 1930 v QM\ OmAexson 11v VENTOR ATTORNEY Patented Jan. 11 1938 METHOD vAND MEANS FOR ABRADING LENSES Carl E. Anderson, Hackensack, N. J., assignor to Banach & Lomb Optical Company, Rochester, N. Y., a corporation of New York Application March '1, 1930," Serial No. 433,934

Renewed May 14, 1937 11 Claims.

This invention relates to thedens grinding and polishing art wherein an abrading tool or lap is moved over the surface of a lens .to. grind or polish it.

In the machines whichcharacterize the prior art a great deal of diificulty has been experienced because the surface of the abrading tool or lap does not wear away uniformly throughout its area. This is due, in part, to the difference in area between the work and the abrading tool, partly to the difference in speed between the work and the tool and partly to the location or position of the abrading surface on the surface of the work.

vide a method and means for abrading-lenses whereby the abrading tool will be worn away substantially uniformly throughout its entire area. Another object is to provide a method and means 20 for abrading lenses wherein the abrading tool and 25 so that the tool is worn away uniformly over its Other objects and advantages reside in surface. certain novel features of construction, arrangement and' combination of parts and in my improved method as will hereinafterbe more fully 30 described and pointed out in the appended claims.

Referring to the drawing;

Fig. 1 shows a sectional View of an apparatus embodying my invention. 7

Fig. 2 is a schematic diagram illustrating the 35 leverlapping relation between the tool and the ens- One embodiment of my invention is illustrated in the drawing wherein L indicates a lens blank which is to be operated upon. The blank L is 40 mounted, by any suitable means, on a block or chuck III which is carried by spindle l I and adapted to'be rotated through the application of suitable power to the pulley l2. A suitable abrading tool or lap I3 is carried by spindle It so that it may be rotated or driven by a belt or other means through the pulley l5.

Thediameter of the abrading tool [3 is substantially equal to the diameter of the lens L so 50 that the area of the abrading surface is substan- One of the objects of this invention is to prolens.

with the axis of the spindle l4 positioned sub stantially at the edge of the lens L.

In operation, the lens L isrotated in one direction and the tool l3 isrotated in the opposite 1 direction, the rotational speeds of the lens and 5 tool being substantially equal. The overlapping of thetool and lens is shown diagrammatically in Fig. 2 wherein the lens and the abrading tool are represented, respectively, by L and I3 and the two arrows show the directions of rotation of the lens and tool. In actual practice, the tool l3 is positioned so that its edge is slightly over the center of the lens L to prevent the formation of a central highspot on the lens. The spindle It could also be oscillated a slight amount so that the tool would pass. slightly over the center of the lens to prevent the formation of a central high spot on the surface of the lens.

Since the edge of the tool is positioned substantially at the center of the lens and since the tool and the lens have substantially the same diameters and rotational speeds, the abrasive action will be substantially uniform over the entire surface of the tool. At a given instant, the contacting area of the lens is substantially equal to the contacting area of the tool so that at the end of a complete revolution the entire area of the tool will have contacted, cumulatively, with a substantially equal area on the surface of the- Hence the abrading action or wearing away of the tool will be substantially uniform over its entire area so that the tool may be used for grinding a large number of lenses without necessitating frequent truing-up of the tool as was required-under prior art methods. My improved method and means may be applied, equally well,

- to either the grinding or polishing of lenses and it is to be understood that the term abrading refers to both grinding and polishing operations.

From the foregoing it will be apparent that I am able to attainthe objects of my invention and provide improved method and means forv abrading lenses wherein the abrading tool will be worn away in a substantially uniform manner over its entire area. Various modifications can obviously be made by persons skilled in the art and it is to be understood that such modifications are to be included withinthe spirit and scope of my invention as defined in the appended claims.

I claim:

1. A method of abrading lenses which comprises rotating an. abrading tool incontact with a lens having substantially the same diameter and area as the tool, holding said tool with its edge positioned substantially at the center of said lens and in contact therewith and rotating said lens at substantially the same speed of rotation as said tool but in an opposite direction.

2. Lens abradingapparatus comprising means for rotating a lens and means for rotating an abrading tool at substantially the same speed as the lens but in the opposite direction, the diameter and area of said tool being substantially the same as the diameter andarea of the lens, the axis of rotation of said tool being located substantially at the edge of said lens.

3. A method of abrading lenses which comprises placing an abrading tool in contact with a lens of the same area and diameter so that the tool projects beyond the edge of the lens, and rotating the tool and the lens so that the linear velocity of any point on the lens plus the linear velocity of the point on the tool which contacts with said point on the lens will be a substantially constant sum. 7

4. Lens abrading apparatus comprising a vertical spindle carrying a block which supports a lens blank, a second spindle mounted above said block, the axis of said second spindle being inclined to the vertical and passing substantially through the edge of the lens blank, a grinding tool rigidly carried on said second spindle, said tool having substantially? the same area and diameter as the lens blank whereby said tool contacts with said blank in overlapping relation and means for rotating said tool and blank at the same speeds but in opposite directions.

5. A method of abrading a lens having a substantially spherical surface which comprises placing in contact with said surface an abrading tool having a spherical abrading surface which has substantially the same diameter and area as the surface on the lens, holding said tool with its center positioned substantially at the edge of said lens and rotating said lens and tool at substantially the same speeds but in opposite directions.

6. A method of abrading lenses which comprises rotating an abrading tool in contact with a lens having substantially the same diameter as the abrading surface of the tool, holding said tool with its abrading surface contacting said lens and with the central part of the abrading surface positioned substantially at the edge of the lens, and rotating said lens at the same speed of rotation as the tool but in an opposite direction.

7. A method of abrading lenses which comaioarvc prises placing a circular abrading tool having a continuous surface in contact with a circular lens having a surface whose area and diameter are substantially the same as the area and diameter of the surface of the tool, holding said tool with its center substantially at the periphery of said lens and rotating said lens and tool in opposite directions but at the same speeds so that the surface speed of any point on the lens plus the surface speed of the point on the tool which contacts with said point on the lens will be a substantially constant sum.

8. Lens grinding means comprising a spindle carrying a block for-supporting a lens, a second spindle mounted above the first spindle and in angular relation thereto, an abrading tool fixedly secured to said spindle, said tool having a substantially continuous spherical surface whose area and diameter are substantially the same as the area and diameter of the lens, said tool being positioned in contact with the lens with its edge substantially at the'center of the lens and means for rotating said spindles at the same speeds but in opposite directions.

9. The method of abrading lenses which comprises placing an abrading tool in contact with a lens of substantially the same area and diameter so that the tool projects beyond the edge of the lens, rotating said lens, and rotating said tool at substantially the same speed as said lens about an axis adjacent the edge of said lens so as to bring substantially the entire area of the lens cumulatively into contact with substantially the entire area of the tool once for each rotation of the lens and tool whereby the wear on the tool will be uniform and the form of the original surface thereon will be preserved.

10. A method of abrading lenses which comprises rotating an abrading tool in contact with a lens having substantially the same diameter and area as said tool, rotating said lens at substantially the same speed of rotation as said tool and oscillating said tool during-rotation.

11. A method of abrading lenses which comprises placing a'lens element in contact with a tool element of substantially the same area. and diameter as said lens element so that the center of the lens element is closely adjacent the edge of said tool-element, rotating said elements at substantially the same speed of rotation and oscillating one of said elements so that the edge of the tool element moves back and forth across the center of the lens element.

CARL' E. ANDERSON. 

